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# In the infinite sequence a1, a2, a3, …, an, an=3(an−1)−1 for all n>1.

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In the infinite sequence a1, a2, a3, …, an, an=3(an−1)−1 for all n>1.  [#permalink]

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16 Apr 2018, 05:44
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Difficulty:

15% (low)

Question Stats:

96% (01:43) correct 4% (00:25) wrong based on 32 sessions

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In the infinite sequence $$a_1$$, $$a_2$$, $$a_3$$, …, $$a_n$$, $$a_n=3(a_{n−1})−1$$ for all n > 1. If $$a_1=1$$, what if the value of $$a_6$$?

A. 41

B. 42

C. 121

D. 122

E. 123

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Re: In the infinite sequence a1, a2, a3, …, an, an=3(an−1)−1 for all n>1.  [#permalink]

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16 Apr 2018, 07:59
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1
Bunuel wrote:
In the infinite sequence $$a_1$$, $$a_2$$, $$a_3$$, …, $$a_n$$, $$a_n=3(a_{n−1})−1$$ for all n > 1. If $$a_1=1$$, what if the value of $$a_6$$?

A. 41

B. 42

C. 121

D. 122

E. 123

$$a_1$$ = 1

$$a_2$$ = 3(1) - 1 = 2

$$a_3$$ = 3(2) -1 = 5

$$a_4$$ = 3(5) -1 = 14

$$a_5$$ = 3(14) -1 = 41

$$a_6$$ = 3(41) -1 = 122

Hence option D = 122 is the answer
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Re: In the infinite sequence a1, a2, a3, …, an, an=3(an−1)−1 for all n>1. &nbs [#permalink] 16 Apr 2018, 07:59
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